Electrical contact device.



J. F. LAMB.

ELECTRICAL CONTACT DEVICE.

APPLICATION FILED mus 23.1915.

1,21 7,964. Patented Mal-.6, 1917.

v Inns/270:: ZWJM L; u zww STATES PATENT OFFICE.

JCSEPHTFRREDRICK LAMB, or NEW nnrrsrm'oonnncrrcvr, ASSIGNOB T LANDERS, I Qr ARY-se CLARK, orNEw BRITAIN, CONNECTICUT.

ELECTRICAL CONTACT DEVICE.

.ToaZZ whom itmay concern:

Be it knownthat I, JOSEPH FREDRICK LAMB, a citizen of the United States, residing at New Britain, inthe county of Hartford and State-of Connecticut, have invented certain new and useful Improvements in Electrical Contact Devices, of which the following is a specification.

My vinvention relates to lmprovements 1n electrical contact devices, and the 0b ect of my improvement is to produce a socket conconditions that prevail in the class of service mentioned, involving simpllcity and e 1 n1y,invention.,..,

economy in construction and convenience and efficiency in use.

Socket contact devices of the class to which my invention applies are made of sheet metal, bent into' generally tubular form, and asevolved in my invention the socket contact device is of triangular form of cross-section, one side wall serving as the main contact member for extending along the plug and the other two side walls serving as holding members for holding the said main member in such contact, and this result is obtained in a more reliable and superior manner by avoiding any gap in the said holding members in the portions of the said holding-members that are directly opposed to the main member and by locating the gap between the opposed free edges of the blank sothat the said gap will be positioned along one edge of the main member.

-In the accompanying drawing;

Figure 1 is a plan view of a complete socket member provided with a pair of sockets and a cord connection, embodying Fig. 2 is an .end elevation of the same.

. Fig. 3 is. aplan view of the parts shown in Fig. 1, with one of the shell members removed. T p

Fig. 4 is Fig.1.,

Fig. 5. is an end elevation of the plug member.

Fig. 6 is a plan view in part broken away of the same.

asectional viewon the line a: w of Specification of Letters Patent.

Patented Mar. 6, 1917.

Fig. 7 is a plan view of the blank for one ofthe sockets.

Fig. 8 is a side elevation of member complete.

Fig. 9 is an end elevationon an enlarged scale ofthe same.

Fig. 10 is sectional View on a reduced scale, on the line g of Fig. 9, the plug bemg shown in position.

Fig. 11 is a sectional view on the line a z of Fig. 8, and on an enlarged scale.

The complete contact device shown in the drawing comprises a pair of my improved socket contact devices 10, in spaced relation, suitable for cooperating witha pair of plug contacts 11, in corresponding spaced relat1on and rigidly .secured Within a. suitable support; such as the shell-like casing 12, the said socket contact devices or sockets 10 being contained in a housing like that shown the socket in the patent to Alonzo A. Warner, No.

1,059,650, April 22, 1913.

The said housing is made of insulating material and comprises a pair ofmating shell members 13 and 14 having opposed faces in abutment, held together by a pair of screws 15, and having coiiperatinggrooves 18 for containing the sockets 10, and the duplex cord 17 connected to the sockets 10 by the individual branches or members 16.

One end .of each socket 10 is connected to the branch cord 16 by means of a terminal screw 19. The active portion 22 of the socket 10 extends from adjacent the terminal screw 19 outwardly to the other-end, the same being of triangular form of cross-section and housed in a portion 20 of the.

grooves or cavities 18 of corresponding form.

The socket 10 is formed of sheet metal, the blank therefor being shown in Fig. 7. The said blank is approximately rectangular, and comprises along one edge the body portion 21 of proper width and length to form one side or the base of the triangular active portion 22, and also to extend. inwardly suitably to receive the terminal screw 19. A plurality of fingers extend outwardly to one side from one-edge of the base 21, comprising the finger 23 at the terminal end and a set of other fingers 24. The finger 23 is shorter than the other fingers, being of suflicient length to be turned back by a return bend, as shown at 25', Fig. 11, so as to cover the terminal end portion 26 of the base 21,

and serve as a reinforcement thereof. After being bent into position as, mentioned, a hole 27 is punched t rough the double thickness of material from the upper sidei through the the terminal screw 19.

A cap of channel form is provided forcooperating with the screw 19 for housing and securing the'strands of the cable or cord 16 comprising the body portion 29 of rectanilar or square form with a central hole or receiving the screw 19 and a gait of dependent flanges 30 at the edges, ttin and extending a ong the 1 edges of the ouble thickness terminal, 23, 26, the cable being housed in the spaces 31 between the screw 19 and the said flanges 30.

The fingers 24 serve as contact fingers, and are of sufiicient length to form the other two sides of the triangular active portion 22, the cross-section of the same be1ng approximately equilateral, there bemg in the finished socket 10 a small open, free space between the free end portions 320i the contact fingers 24 and the opposed edge of the basev 31. The two corners of each of the said free end portions 32 of the cont-actfingers 24 are clipped, as shown'at 33, whereby the said free end portions 32 are generally of tapered form.

As stated, the sockets 10 are made of sheet material, and the same is of sutlicient strength so that when used in pairs as described the combined weight of the connected parts, consisting of the shell members 13 and 14 and the cable end 17, will be positively supported by the engagement of the two sockets 10 with the two contact pins 11, and such positive support is provided even when the sockets 10 are only partially entered on the pins 11, such as w en only the outermost contact fingers 24 are engaged with the pins 11. Such support is furthermore provided independent of the inclosing housing provided by the shell members 13 and 14.

Accordingly, each contact finger 24 combines with the base 21 to form a complete individual connecting socket, independent of the other adjacent finger 24. The advantage of this arrangement is that under normal conditions of use, with all the contact fingers 24 engaged with the ins 11, each of the said individual sockets is active, and they all cooperate to deliver current, a condition that is especially desirable for certain household implements that require an appreciable quantit of current,imperfect contact increases t e drop and causes exmive heating of the contacts.

Furthermore, by providing for s lurality of individual contact sockets as ascribed the condition of maximum active contact descri pertains even with slight inaccuracies in the contact pins 11, such as are liable to occur when such contact pins 11 are produced commercially in large quantities. For instance, the pins 11 are sup; posed to be of cylindrical form for t active portion, whereas actually they ma be slightly tapered, to the extent of asma fraction of an inch. Notwithstanding this condition the plurality of individual sockets provided as described always insures a proper and full contact.

Considering the feature of the triangular form of the active 'on 22, and particularly the individua sockets of which the same is composedfit will be noted that the contact points are distributed around the periphery of the pins 11 at esentially equidistant points or lines. The fin rs 24 are set so that a sli ht opening out o the socket is required in sipping the socket along the in 11, and because of the trian In reation, all of the sides of the triang e are active, and they adust themselves under the pressure due to the resiliency of the material, so that all are held in engagement with the pin by the same contact pressure. The

socket 22 as describedis formed by folding a sheet. metal blank, leaving a small free 0 space between the 0p 0 0 u edges of the bank. It will be 11 u that I have so formed the blank and folded the same that the said opening is provided along one edge of the fiat base or main member 21, between the said edge and the ends 23 of the fingers 24, and in lieu of an open space directly opposed to the main member 21 there is a closed hook-like formation of the fingers 24. Thus the fingers 24 are adapted to serve as holding members to hold the main memberv 21 in contact with the portion of the plug opposed thereto, whether fully or only partially entered on the plug, and notwithstanding any relative shifting or twistin of the plug and socket so as to be out o alinement such as ma be etl'ected by the weight of the cord or movements of the operator, particularly in such devices as sad-irons.

The clipping of the corners 38 adds to the 'fiexibility of the contact fingers 24 and facilitates the en gementthereof with the pins 11, particu arly in case of slight inaccuracies of alinement of the sockets 10 and the pins 11 as they are brought into engagement.

As described, the finger 23, connected to the terminal extension 26 of the base 21 by a return head, is superimposed on the said extension 26 and serves as a reinforcing layer, and the said la er and extension as a unit are provided wit a threaded hole for a terminal screw, and material from the said layer and extension forming the border walls of the said hole is extended axially so as to extend the screw threaded wall below the face-of the said extension. Thus material of the said layer overlaps material of the said extension and the overlapping portions are forcibly interlocked, one with the other.

I claim as my invention 1. A socket for a plug connection formed from a blank of sheet metal, bent into tubular form, comprising in combination a main member in the form of a fiat spring suitable for extending alon one side of the plug, and being extended ongitudinally to provide means for receiving a terminal connection, a plurality of fingers opposed to the said main member, serving as holding members for holding the said main member in contact with the plug, the said fingers extending continuously over the face of the said main member, being bent to form the other two sides of the said socket, being each connected b one end to one edge of the said main member, and the other ends of the said holding members being opposed to the other edge of the said main member 'and separated therefrom by an open space.

2. A blank for a contact socket made of sheet metal of approximately rectangular form, comprising a continuous strip along one side, and having fingers extending laterally from one edge of the said strip toward the other side, one of the said fingers being at one end and of suitable length to be turnedback by'a return bend against the said strip to reinforce the same, and the others of the said fingers comprising a set of similar fingers of suitable length to be bent individually transversely and to be positioned by a bend at the junction with the said strip to form with the said strip a contact socket of triangular cross-section.

3. A socket connecting member for a plug connection made of sheet material, comprising a socket portion composed of a base and a plurality of contact fingers connected to the said base, an extension of the said base serving as a terminal portion, the said extension being reinforced by a superimposed layer of material connected by a return bend, the said layer and extension being provided with a threaded hole for a terminal screw, and the material of the said layer and extension .forming the border Walls of the said hole being'extende'd axially to interlock the said layer and extension and to extend the screw threaded wall below the face of the said extension.

JOSEPH FREDRICK Witnesses:

HENRY FAGAN, CATHERINE SoANLoN.

SO as. 

